There are no GIFs on the GNU web site because of the
patents (Unisys and IBM) covering
the LZW compression algorithm
which is used in making GIF files. These patents make it
impossible to have free software to generate proper GIFs.
They also apply to the compress program, which is why
GNU does not use it or its format.

Unisys and IBM both applied for patents in 1983. Unisys (and perhaps
IBM) applied for these patents in a number of countries. Of the
places whose patent databases we were able to search, the latest
expiration date seems to be 1 October 2006.
1 Until then,
anyone who releases a free program for making GIF files
is likely to be sued. We don't know any reason to think that the
patent owners would lose these lawsuits.

If we released such a program, Unisys and IBM might think it wiser
(for public relations reasons) not to sue a charity like the FSF.
They could instead sue the users of the program, including the
companies who redistribute GNU software. We feel it would not be
responsible behavior for us to set up this situation.

Many people think that Unisys has given permission for distributing
free software to make GIF format. Unfortunately that is
not what Unisys has actually done. Here is what Unisys actually said
about the matter in 1995:

Unisys does not require licensing, or fees to be paid, for
non-commercial, non-profit GIF-based applications,
including those for use on the on-line services. Concerning
developers of software for the Internet network, the same principle
applies. Unisys will not pursue previous inadvertent infringement by
developers producing versions of software products for the Internet
prior to 1995. The company does not require licensing, or fees to be
paid for non-commercial, non-profit offerings on the Internet,
including “Freeware”.

Unfortunately, this doesn't permit
free software which can be used
in a free operating system such as GNU. It also does not
permit at all the use of LZW for other purposes
such as compression of files. This is why we think it is still best
to reject LZW, and switch to alternatives such
as GNU Gzip
and PNG.

Commercial redistribution of free
software is very important, and we want the GNU system as a whole
to be redistributed commercially. This means we can't add
a GIF-generating program to GNU, not under the Unisys
terms.

The Free Software Foundation is a
non-commercial, non-profit organization, so strictly speaking the
income from our sales of CD-ROMs
is not “profit”. Perhaps this means we could include
a GIF program on our CD-ROM and claim to be acting within
the scope of the Unisys permission—or perhaps not. But since we
know that other redistributors of GNU would be unable to include it,
doing this would not be very useful.

Shortly after Unisys made its announcement, when the net in general
was reassured thinking that Unisys had given permission for
free GIF-generating software, we wrote to the Unisys
legal department asking for clarification of these issues. We did not
receive a response.

Even if Unisys really did give permission for free software to
generate GIFs, we would still have to deal with the IBM
patent. Both the IBM and the Unisys patents cover the same
“invention”—the LZW compression
algorithm. (This could reflect an error on the part of the US Patent
and Trademark Office, which is famous for incompetence and poor
judgment.)

Decoding GIFs is a different issue. The Unisys and IBM
patents are both written in such a way that they do not apply to a
program which can only uncompress LZW format and cannot
compress. Therefore we can and will include support for
displaying GIF files in GNU software.

Given this situation, we could still include GIF files in
our web pages if we wanted to. Many other people would be happy to
generate them for us, and we would not be sued for
having GIF files on our server.

But we feel that if we can't distribute the software to enable people
to generate GIF files properly, then we should not have
other people run such software for us. Besides, if we can't provide
software in GNU to generate GIF files, we have to
recommend an alternative. We ourselves should use the alternative
that we recommend.

In 1999, Unisys had the following to say about the issue of their
patent:

Unisys has frequently been asked whether a Unisys
license is required in order to use LZW software obtained
by downloading from the Internet or from other sources. The answer is
simple. In all cases, a written license agreement or statement signed
by an authorized Unisys representative is required from Unisys for all
use, sale or distribution of any software (including so-called
“freeware”) and/or hardware providing LZW
conversion capability (for example, downloaded
software).

With this statement, Unisys is trying to take back what they said in
1995 when they gave parts of the patent to the public. The legality of
such a move is questionable.

A further issue is that the LZW patents—and computational idea
patents in general—are an offense against the freedom of
programmers generally, and all programmers need to work together
to protect
software from patents.

So even if we could find a solution to enable the free software
community to generate GIFs, that isn't really a solution,
not for the problem as a whole. The solution is switching to another
format and not using GIF any more.

Therefore, we don't use GIF, and we hope you won't use it
either.

It is possible to make non-compressed images that act
like GIFs, in that they work with programs that
decode GIF format. This can be done without infringing
patents. These pseudo-GIFs are useful for some purposes.

It is also possible to create GIFs using a patent-free
run length encoding but this doesn't achieve the compression that one
normally expects in a GIF.

We decided not to use these pseudo-GIFs on our web site
because they are not a satisfactory solution to the community's
problem. They work, but they are very large. What the web needs is a
patent-free compressed format, not large pseudo-GIFs.

The PNG
format is a patent-free compressed format. We hope it will become
widely supported; then we will use it. We do provide PNG versions of
most of the images on this server.

Footnote:

1. We were able to search
the patent databases of the USA, Canada, Japan, and the European
Union. The Unisys patent expired on 20 June 2003 in the USA, in Europe
it expired on 18 June 2004, in Japan the patent expired on 20 June
2004 and in Canada it expired on 7 July 2004. The U.S. IBM patent
expired 11 August 2006. The Software Freedom Law Center says that
after 1 October 2006, there will be no significant patent claims
interfering with the use of static GIFs.

Animated GIFs are a different story. We do not know what patents
might cover them. However, we have not heard reports of threats
against use of animated GIFs. Any software can be threatened by
patents, but we have no reason to consider animated GIFs to be in
particular danger — no particular reason to shun them.